Backlighting is a common feature of many keypads, switches and other devices. As the name suggests, it’s a lighting system found in the rear or back of a device. When you turn on the device, the backlighting will illuminate it. While some devices use light-emitting diode (LED) backlighting, though, others use electroluminescent (EL) backlighting.

What Is EL Backlighting?

EL backlighting is a specific type of backlighting that leverages the light-generating properties of an electroluminescent material, such as phosphor. Like all other types of backlighting, it’s used to illuminate devices. Keypads, switches and other devices often feature backlighting. EL backlighting will illuminate them so that the keys, buttons and legends on them are easier to see.

There are different types of backlighting. EL is a specific type of backlighting that lives up to its namesake by featuring an electroluminescent material. The electroluminescent material is responsible for generating the light. Now that you know what EL backlighting is, you might be wondering how it works.

How EL Backlighting Works

EL backlighting works by generating light in response to an electrical current. The term “electroluminescent” is used to describe materials that illuminate as electricity flows through them. Phosphor falls under this category. When electricity flows through phosphor, it will generate light.

It’s important to note that phosphor isn’t a specific element on the Periodic Table. Rather, it’s a host material that contains an activator. Phosphor may consist of copper-activated zinc sulfide, or it may consist of silver-activated zinc sulfide. Regardless, phosphor consists of a host material, such as zinc sulfide, along with an activator, such as copper or silver.

Some of the benefits of EL backlighting include:

  • Long-lasting
  • Energy efficient
  • Reliable
  • Saves space

The Construction of EL Backlighting Systems

There are different ways to construct EL backlighting systems. Many keypads and switches, though, use a phosphor-based layer. They feature a layer of phosphor that’s sandwiched between two conductive layers. This otherwise simple construction offers an effective and reliable backlighting system.

An electrical current is applied to the two conductive layers. Because the layers are conductive, electricity will flow through them. Electricity will travel through the two conductive layers and the phosphor-based layer between them. As electricity flows through the phosphor-based layer, it will illuminate. There are other ways to construct EL backlighting systems, but many keypads and witches use a phosphor-based layer sandwiched between two conductive layers.